The present invention relates to an apparatus for producing compost by achieving an aerobic fermentation of organic wastes and excretions, which are of relative fluidity or high water content, such as a mixture of feces and urine of domestic animals.
Conventionally, rotary kilns have been used wherein organic wastes are aerobically fermented to produce compost. However, the conventional apparatus has presented some serious disadvantages in that a great number of rotary kilns, which are expensive must be installed when a further amount of organic wastes are treated since there is a definite limitation in constructing large-scaled kilns. Further, after the kilns are formed on a larger scale, the predetermined large amount of wastes should always be treated in order to keep the desired fermentation condition within the kilns. Thus, the kilns in the conventional art are almost inapplicable to variations in volume of the wastes to be treated.
On the other hand, an attempt has been made recently in which piled organic wastes are circulated within an annular groove to achieve an aerobic fermentation of wastes during circulation. In the attempt, the piled organic wastes, which have been supplied into the preformed annular groove for fermentation, are circularly transferred along the groove by means of rotary stirrers and the fermentation and a natural drying are carried out during such circulation. After the natural drying is completed to obtain compost which contains water of about 20% by weight, a part of the naturally dried compost is delivered out of a predetermined position of the groove, and then crude or unfermented organic wastes are additionally supplied onto the remanent compost in the groove. Then, another stirring is done while the mixture of the newly supplied organic wastes and the remanent compost are circularly transferred along the groove for another fermentation.
In this annular groove type apparatus, disadvantageous problems have also appeared in that the apparatus should have an annular groove having an extraordinarily large area since an aerobic fermentation is generally restricted to a piling height of, at most, about 50 cm. Thus, if the height of the mixture of the residual fermented composts and the crude organic wastes exceeds about 50 cm, the desired aerobic fermentation will no longer be effected. Further, the conventional apparatus, in which the mixture to be fermented is not only stirred but is also transferred along the groove, requires considerable power for transferring the mixture, particularly when a great amount of mixture is treated. Moreover, the conventional apparatus requires an additional element such as housing or casing which covers the whole structure of the apparatus to maintain the fermentation temperature and prevent terrible odors.
Accordingly, an object of the present invention is to provide a novel apparatus for producing compost, which allows an efficient fermentation.
Another object of the present invention is to provide an apparatus for producing compost, which allows a desired aerobic fermentation even when the material to be fermented is piled one meter high and more.
A further object of the present invention is to provide an apparatus for producing composts, which provides a stirring and mixing step, an aerobic fermentation step and drying step within a single vessel, without transferring all of the piled mixture.